Colletotrichum spp. causing anthracnose on ornamental plants in northern Italy

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ORIGINAL ARTICLE

Colletotrichum spp. causing anthracnose on ornamental plants in northern Italy Vladimiro Guarnaccia 1,2

&

Ilaria Martino 1 & Giovanna Gilardi 1 & Angelo Garibaldi 1 & M. Lodovica Gullino 1,2

Received: 3 May 2020 / Accepted: 9 October 2020 # The Author(s) 2020

Abstract Species of Colletotrichum are considered among the most important plant pathogens, saprobes and endophytes on a wide range of ornamentals, fruits and vegetables. Several Colletotrichum species have been reported in nurseries and public or private gardens in northern Italy. In this study, the occurrence, diversity and pathogenicity of Colletotrichum spp. associated with several ornamental hosts was explored. Survey were carried out during the 2013–2019 period in Piedmont, Italy. A total of 22 Colletotrichum isolates were collected from symptomatic leaves and stems of two Campanula spp., Ceanothus thyrsiflorus, Coreopsis lanceolata, Cyclamen persicum, Hydrangea paniculata, Liquidambar styraciflua, Mahonia aquifolium and Rhyncospermum jasminoides. A multi-locus phylogeny was established based on the basis of three genomic loci (gapdh, act and tub2). The pathogenicity of selected, representative isolates was tested. Colletotrichum isolates were identified as members of four important species complexes: Acutatum, Gloeosporioides, Dematium and Destructivum. Colletotrichum fioriniae, C. nymphaeae and C. fuscum were found in association with leaf lesions of Mahonia aquifolium, Campanula rapunculoides and Coreopsis lanceolata, respectively. Colletotrichum lineola, C. grossum and C. cigarro were isolated from Campanula trachelium, Rhyncospermum jasminoides and Liquidambar styraciflua, respectively. Colletotrichum fructicola was found to be responsible of anthracnose of Ceanothus thyrsiflorus, Hydrangea paniculata, Cyclamen persicum and Liquidambar styraciflua. All the tested isolates were pathogenic and reproduced identical symptoms to those observed in private gardens and nurseries. The present study improves our understanding of Colletotrichum spp. associated with different ornamental hosts and provides useful information for an effective disease management programme. Keywords Leaf spot . Multi-locus sequence typing . Pathogenicity . Species complex

Introduction The genus Colletotrichum has been reported as one of the ten most important plant pathogens in the world based on economic importance (Dean et al. 2012). Anthracnose disease caused by species members of this genus could affect several plants from woody to herbaceous ones, producing significant economic losses in tropical, subtropical and temperate regions. They can develop on fruit, leaves, stems, tubers and * Vladimiro Guarnaccia [email protected] 1

Centre for Innovation in the Agro-Environmental Sector, AGROINNOVA, University of Torino, Largo Braccini 2, TO 10095 Grugliasco, Italy

2

Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, Largo Braccini 2, TO 10095 Grugliasco, Italy

seedlings in the field or in greenhouse environment